In light of the disastrous unraveling of Japan’s nuclear facilities, the Obama administration moved swiftly to reassure an anxious public that reactors in the United States are safe.

“The American people should have full confidence that the United States has rigorous safety regulations in place to ensure that our nuclear power is generated safely and responsibly,” Energy Secretary Steven Chu told the House of Representatives Appropriations Subcommittee on Energy and Water Development.

He also added that officials are “committed to learning from Japan’s experience as we work to continue to strengthen America’s nuclear industry.”

But for skeptics, what’s particularly worrisome is the fact that the U.S. has in operation 23 General Electric Mark 1 nuclear reactors, the same type of reactor that’s dangerously veering toward a possible meltdown. And a report in the New York Times has uncovered decades-old memos from high-ranking energy officials that warned of flaws in the reactor’s containment vessel, a structure that serves as the last line of defense in case the cooling system malfunctions.

In 1972, Stephen H. Hanauer, a safety official with the Atomic Energy Commission wrote up an an assessment of the Mark 1’s containment design and recommended that the agency adopted a policy “discouraging the use of such “pressure-suppression containment” and that such a design “not be accepted for construction permits” for the time being.

Joseph Hendrie, who later served as the chairman of the Nuclear Regulatory Commission, acknowledged that Hanauer’s proposed course of action was “attractive,” but decided against moving forward with the suggestions. His reasoning was that “reversal of this hallowed policy, particularly at this time, could well be the end of nuclear power.”

At the time, nuclear energy was still trying to gain footing as an alternative to oil and GE opted for a comparably smaller containment vessel design because it allowed for cheaper and easy-to-build reactors.

The New York Times report goes on to say:

Questions about the G.E. reactor design escalated in the mid-1980s, when Harold Denton, an official with the N.R.C., asserted that Mark 1 reactors had a 90 percent probability of bursting should the fuel rods overheat and melt in an accident. A follow-up report from a study group convened by the commission concluded that “Mark 1 failure within the first few hours following core melt would appear rather likely.”

In an extreme accident, that analysis held, the containment could fail in as little as 40 minutes.

In reaction to what they company felt was unwarranted finger-pointing, GE issued a statement defending the Mark 1 reactor as “the industry’s workhorse with a proven track record of safety and reliability for more than 40 years.” The company also pointed out that “there has “never been a breach of a Mark 1 containment system.”

To be fair, Mark 1 reactors in the U.S. have since been retrofitted with a series of safety enhancements to compensate for potential vulnerabilities. These features include a venting system and modifications to the torus, a water-filled vessel used to reduce pressure build-up in the reactor.

Also, It’s debatable whether a bigger, studier containment vessel would have fared any better in the face of a tsunami or any other devastating natural disaster.

Contributing Editor
Tuan C. Nguyen is a freelance science journalist based in New York City. He has written for the U.S. News and World Report, Fox News, MSNBC, ABC News, AOL, Yahoo! News and LiveScience. Formerly, he was reporter and producer for the technology section of ABCNews.com. He holds degrees from the University of California...
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